libcpp: Fix up pragma preprocessing [PR100450]

Message ID 20210507075329.GG1179226@tucnak
State New
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  • libcpp: Fix up pragma preprocessing [PR100450]
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Commit Message

Andre Vehreschild via Gcc-patches May 7, 2021, 7:53 a.m.
Hi!

Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c
https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html
changes, so that we handle macros inside of pragmas that should expand
macros, during preprocessing we print those pragmas token by token,
with CPP_PRAGMA printed as
      fputs ("#pragma ", print.outf);
      if (space)
        fprintf (print.outf, "%s %s", space, name);
      else
        fprintf (print.outf, "%s", name);
where name is some identifier (so e.g. print
#pragma omp parallel
or
#pragma omp for
etc.).  Because it ends in an identifier, we need to handle it like
an identifier (i.e. CPP_NAME) for the decision whether a space needs
to be emitted in between that #pragma whatever or #pragma whatever whatever
and following token, otherwise the attached testcase is preprocessed as
#pragma omp forreduction(+:red)
rather than
#pragma omp for reduction(+:red)
The cpp_avoid_paste function is only called for this purpose.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk
and release branches (in particular 8 which freezes later today)?

2021-05-07  Jakub Jelinek  <jakub@redhat.com>

	PR c/100450
	* lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

	* c-c++-common/gomp/pr100450.c: New test.


	Jakub

Comments

Andre Vehreschild via Gcc-patches May 7, 2021, 2:58 p.m. | #1
On Fri, May 07, 2021 at 09:53:29AM +0200, Jakub Jelinek wrote:
> Hi!

> 

> Since the r0-85991-ga25a8f3be322fe0f838947b679f73d6efc2a412c

> https://gcc.gnu.org/legacy-ml/gcc-patches/2008-02/msg01329.html

> changes, so that we handle macros inside of pragmas that should expand

> macros, during preprocessing we print those pragmas token by token,

> with CPP_PRAGMA printed as

>       fputs ("#pragma ", print.outf);

>       if (space)

>         fprintf (print.outf, "%s %s", space, name);

>       else

>         fprintf (print.outf, "%s", name);

> where name is some identifier (so e.g. print

> #pragma omp parallel

> or

> #pragma omp for

> etc.).  Because it ends in an identifier, we need to handle it like

> an identifier (i.e. CPP_NAME) for the decision whether a space needs

> to be emitted in between that #pragma whatever or #pragma whatever whatever

> and following token, otherwise the attached testcase is preprocessed as

> #pragma omp forreduction(+:red)

> rather than

> #pragma omp for reduction(+:red)

> The cpp_avoid_paste function is only called for this purpose.


Nice explanation, it helped me to understand this.
 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk

> and release branches (in particular 8 which freezes later today)?


OK.  I don't think we'd ever want to actually concatenate in this context.
 
> 2021-05-07  Jakub Jelinek  <jakub@redhat.com>

> 

> 	PR c/100450

> 	* lex.c (cpp_avoid_paste): Handle token1 CPP_PRAGMA like CPP_NAME.

> 

> 	* c-c++-common/gomp/pr100450.c: New test.

> 

> --- libcpp/lex.c.jj	2021-05-04 21:02:13.633917100 +0200

> +++ libcpp/lex.c	2021-05-06 20:32:07.695035739 +0200

> @@ -3709,6 +3709,7 @@ cpp_avoid_paste (cpp_reader *pfile, cons

>      case CPP_DEREF:	return c == '*';

>      case CPP_DOT:	return c == '.' || c == '%' || b == CPP_NUMBER;

>      case CPP_HASH:	return c == '#' || c == '%'; /* Digraph form.  */

> +    case CPP_PRAGMA:

>      case CPP_NAME:	return ((b == CPP_NUMBER

>  				 && name_p (pfile, &token2->val.str))

>  				|| b == CPP_NAME

> --- gcc/testsuite/c-c++-common/gomp/pr100450.c.jj	2021-05-06 20:33:45.302961055 +0200

> +++ gcc/testsuite/c-c++-common/gomp/pr100450.c	2021-05-06 20:33:39.882020738 +0200

> @@ -0,0 +1,20 @@

> +/* PR c/100450 */

> +/* { dg-do compile } */

> +/* { dg-options "-fopenmp -save-temps -Wunknown-pragmas" } */

> +

> +#define TEST(T) { \

> +     {T} \

> +}

> +#define CLAUSES reduction(+:red)

> +#define PARALLEL_FOR(X) TEST({ \

> +_Pragma("omp for CLAUSES") \

> +X \

> +})

> +

> +void foo()

> +{

> +  int red = 0;

> +  int A[3] = {};

> +  #pragma omp parallel shared(red)

> +  PARALLEL_FOR( for(int i=0; i < 3; i++) red += A[i]; )

> +}

> 

> 	Jakub

> 


Marek

Patch

--- libcpp/lex.c.jj	2021-05-04 21:02:13.633917100 +0200
+++ libcpp/lex.c	2021-05-06 20:32:07.695035739 +0200
@@ -3709,6 +3709,7 @@  cpp_avoid_paste (cpp_reader *pfile, cons
     case CPP_DEREF:	return c == '*';
     case CPP_DOT:	return c == '.' || c == '%' || b == CPP_NUMBER;
     case CPP_HASH:	return c == '#' || c == '%'; /* Digraph form.  */
+    case CPP_PRAGMA:
     case CPP_NAME:	return ((b == CPP_NUMBER
 				 && name_p (pfile, &token2->val.str))
 				|| b == CPP_NAME
--- gcc/testsuite/c-c++-common/gomp/pr100450.c.jj	2021-05-06 20:33:45.302961055 +0200
+++ gcc/testsuite/c-c++-common/gomp/pr100450.c	2021-05-06 20:33:39.882020738 +0200
@@ -0,0 +1,20 @@ 
+/* PR c/100450 */
+/* { dg-do compile } */
+/* { dg-options "-fopenmp -save-temps -Wunknown-pragmas" } */
+
+#define TEST(T) { \
+     {T} \
+}
+#define CLAUSES reduction(+:red)
+#define PARALLEL_FOR(X) TEST({ \
+_Pragma("omp for CLAUSES") \
+X \
+})
+
+void foo()
+{
+  int red = 0;
+  int A[3] = {};
+  #pragma omp parallel shared(red)
+  PARALLEL_FOR( for(int i=0; i < 3; i++) red += A[i]; )
+}